KR20130140784A - Polypropylene resin composition for injection molding, and molded article - Google Patents

Abstract

The polypropylene resin composition for injection molding of the present invention is a polypropylene resin composition for injection molding containing a propylene-based resin material and a crystallization nucleating agent, and has an intrinsic viscosity of 0.8-1.4 dl / g of xylene soluble powder and a melt flow rate. It is 5-15 g / 10min, and the said propylene resin material uses the ethylene 1-butene copolymer which 74-86 mass% of ethylene units are in presence of the ethylene propylene copolymer of 2.0-4.0 mass% of ethylene units. It is what superposed | polymerized and content of the ethylene 1-butene copolymer when 10 mass% of polypropylene resin compositions for injection molding is 10-20 mass%. According to this invention, the polypropylene resin composition for injection molding which is excellent in transparency, whitening resistance, and low temperature impact strength can be provided.

Description

POLYPROPYLENE RESIN COMPOSITION FOR INJECTION MOLDING, AND MOLDED ARTICLE}

The present invention relates to a polypropylene resin composition suitable for injection molding and a molded article obtained by injection molding the resin composition.

This application claims priority based on patent application 2010-279656 for which it applied to Japan on December 15, 2010, and uses the content here.

Polypropylene resin compositions containing polypropylene as a main component are not only inexpensive but also excellent in mechanical properties, and are widely used in various applications such as clothing cases and food containers.

In clothing cases and containers, transparency is required in order to make the objects visible. In addition, high impact strength is required to prevent breakage during transport and use. Moreover, when it has a hinge part, the whitening resistance at the time of bending is calculated | required. In addition, since the clothes case and the containers are molded by injection molding, injection moldability is also required.

Conventionally, in the molded article which requires transparency, the resin composition which contains the random copolymer of ethylene propylene as a main component described in patent document 1 is used. Moreover, in the molded article which high impact strength is calculated | required, the resin composition containing the block polypropylene described in patent document 2, 3 as a main component is used.

Japanese Patent Publication No. 2008-540756 Japanese Laid-Open Patent Publication No. 7-3087 Japanese Patent Laid-Open No. 9-31264

However, the molded article obtained from the resin composition of patent document 1 may become inadequate impact strength, especially the impact strength in low temperature. The molded article obtained from the resin compositions of patent documents 2 and 3 may become inadequate in transparency and whitening resistance.

An object of the present invention is to provide a polypropylene resin composition for injection molding and a molded article excellent in transparency, whitening resistance and low temperature impact strength.

The polypropylene resin composition for injection molding of the present invention is a polypropylene resin composition for injection molding containing a propylene resin material and a crystallization nucleating agent, and has an intrinsic viscosity of 0.8 to 1.4 dl of xylene soluble component in tetrahydronaphthalene at 135 ° C. / g, a melt flow rate measured at a temperature of 230 ° C. and a load of 21.6 N in accordance with Japanese Industrial Standard JIS K 7210 is 5 to 15 g / 10 minutes, and the propylene resin material has an ethylene unit of 2.0 to 4.0 mass. Ethylene 1 when polymerizing an ethylene 1-butene copolymer having an ethylene unit of 74 to 86% by mass in the presence of an ethylene / propylene copolymer of 2% and making the polypropylene resin composition for injection molding 100% by mass. Content of a butene copolymer is 10-20 mass%.

In the polypropylene resin composition for injection molding of the present invention, the content of the crystallization nucleating agent is 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the propylene resin material.

The molded article of the present invention is injection molded of the polypropylene resin composition for injection molding.

The polypropylene resin composition for injection molding of the present invention is excellent in transparency, whitening resistance and low temperature impact strength, and is suitable for injection molding.

The polypropylene resin composition for injection molding (hereinafter abbreviated as "resin composition") of the present invention contains a propylene resin material and a crystallization nucleating agent.

In the resin composition of this invention, it is preferable that the intrinsic viscosity of the xylene solubles in 135 degreeC tetrahydro naphthalene is 0.8-1.4 dl / g, and is 0.8-1.2 dl / g. When the intrinsic viscosity of a resin composition exceeds the said upper limit, there exists a tendency for whitening resistance and transparency to fall. Although the intrinsic viscosity of the xylene soluble component of a resin composition largely depends on the viscosity of an ethylene 1-butene copolymer, it is difficult to manufacture a propylene resin material for making intrinsic viscosity below the said lower limit.

Moreover, it is preferable that melt flow rate (MFR) of a resin composition is 5-15 g / 10 minutes, and is 8-12 g / 10 minutes. Here, MFR is the value measured on condition of temperature 230 degreeC and a load of 21.6N based on JISK7110. Injection moldability falls that MFR of a resin composition is less than the said lower limit, and low temperature impact strength falls when the said upper limit is exceeded.

(Propylene-based resin material)

The propylene resin material is a reaction blended polypropylene obtained by polymerizing an ethylene-1-butene copolymer in the presence of an ethylene / propylene copolymer in a polymerization reactor. In addition, an ethylene 1-butene copolymer is a rubber component.

Productivity becomes high by polymerizing an ethylene 1-butene copolymer in presence of an ethylene propylene copolymer. Moreover, since the dispersibility of a material becomes high, the physical property balance also improves.

The propylene resin material can be produced by multistage polymerization. For example, the ethylene-propylene copolymer is polymerized in the first stage polymerization reactor, the obtained ethylene-propylene copolymer is supplied to the second stage polymerization reactor, and the ethylene-1-butene copolymer is polymerized in the second stage polymerization reactor. By doing so, a propylene resin material can be obtained. In this method, the ethylene-propylene copolymer and the resulting ethylene-butene copolymer are mixed in the second stage polymerization reactor.

In addition, a multistage superposition | polymerization is not limited to the said method, You may superpose | polymerize an ethylene propylene copolymer in several polymerization reactors, and you may superpose | polymerize an ethylene 1-butene copolymer in several polymerization reactors.

Although a well-known olefin polymerization catalyst can be used as a catalyst used for superposition | polymerization, a Ziegler-Natta catalyst is preferable at the point which can easily manufacture the propylene resin material which expresses a desired physical property among these.

In addition, in the case of superposition | polymerization, you may add hydrogen for adjustment of MFR as needed.

Ethylene unit content in an ethylene propylene copolymer is 2.0-4.0 mass%, and it is more preferable that it is 3.0-4.0 mass%. When content of the ethylene unit in an ethylene propylene copolymer exceeds the said upper limit, there exists a tendency for manufacture of a propylene resin material to become difficult, and when it is less than the said lower limit, the transparency and low temperature impact strength of the resin composition obtained may fall. have.

Ethylene unit content in an ethylene 1-butene copolymer is 74-86 mass%, and it is preferable that it is 79-84 mass%. When the ethylene unit content in the ethylene-1-butene copolymer exceeds the above upper limit, there is a tendency that the low temperature impact strength of the resin composition to be obtained is lowered, and when the ethylene unit content is less than the lower limit, the production of propylene resin material becomes difficult. In addition, the rigidity and transparency of a resin composition may fall.

Content of the ethylene 1-butene copolymer in a resin composition is 10-20 mass% at the time of making a resin composition 100 mass%, and it is preferable that it is 12-16 mass%. When content of an ethylene 1-butene copolymer exceeds the said upper limit, rigidity will fall, and when it is less than the said lower limit, there exists a tendency for the low temperature impact strength of the resin composition obtained to fall.

(Crystallization nucleating agent)

The crystallization nucleating agent promotes the formation of polypropylene crystal nuclei and improves the transparency and rigidity of the resin composition obtained. By including a crystallization nucleating agent, haze value (JIS K 7105, 1 mm thickness) can be easily made into 30% or less.

Specific examples of the crystallization nucleating agent include sorbitol compounds, metal salts of carboxylic acids, aromatic phosphate ester compounds, silica, talc and the like. In view of low odor, an aromatic phosphate ester compound is preferable.

Examples of the sorbitol compound include dibenzylidene sorbitol, 1,3,2,4-di (methylbenzylidene) sorbitol, 1,3,2,4- (ethylbenzylidene) sorbitol, 1,3,2 , 4- (methoxybenzylidene) sorbitol, 1,3,2,4- (ethoxybenzylidene) sorbitol, 1,2,3-trideoxy-4,6-5,7-bis-o- [ (4-propylphenyl) methylene] nonitol, etc. are mentioned.

As a metal salt of carboxylic acid, for example, sodium adipic acid, potassium adipic acid, aluminum adipic acid, sodium sebarate, potassium sebarate, aluminum sebacate, sodium benzoate, aluminum benzoate, di-para-t Aluminum butylbenzoate, di-para-t-butylbenzoate titanium, di-para-t-butylbenzoate chromium, hydroxy-di-t-butylbenzoate, and the like.

Moreover, triamino benzene derivative can be used as a crystallization nucleating agent.

It is preferable that it is 0.01-0.5 mass part with respect to 100 mass parts of propylene resin materials, and, as for content of a crystallization nucleating agent, it is more preferable that it is 0.1-0.4 mass part. However, when a crystallization nucleating agent is a triamino benzene derivative, it is preferable that it is 0.01-0.02 mass part. If content of a crystallization nucleating agent is more than the said lower limit, transparency of the molded article obtained from a resin composition can be improved more, and if it is below the said upper limit, odor can be suppressed.

(Other polymer)

Another polymer may be contained in a resin composition as needed.

As other polymers, known thermoplastic resins or thermosetting resins can be used.

Examples of the thermoplastic resins include ethylene or α-olefin homopolymers, ethylene or copolymers of 3 to 10 carbon atoms, and mixtures thereof, nylon, polycarbonates, polyphenylene oxides, petroleum resins, and the like. Can be.

As the ethylene or α-olefin homopolymer, for example, high density polyethylene, low density polyethylene, polypropylene, poly-1-butene, poly-1-pentene, poly-1-hexene, poly (3-methyl-1-pentene ), Poly (3-methyl-1-butene), poly (4-methyl-1-pentene), poly-1-hexene, poly-1-heptene, poly-1-octene, poly-1-decene, polystyrene and A combination of these. Among these, polypropylene is preferable.

(additive)

In the resin composition of this invention, as an arbitrary component, antioxidant, a hydrochloric acid absorber, a heat stabilizer, an optical stabilizer, an ultraviolet absorber, an internal lubricant, an external lubricant, an antistatic agent, a flame retardant, a dispersing agent, a copper anti-inflammatory agent, a neutralizing agent, for example Additives, such as a plasticizer, a foaming agent, an antifoaming agent, a crosslinking agent, and a peroxide, may be included.

(Manufacturing method)

The resin composition described above is blended with a propylene resin material, a crystallization nucleating agent, other polymers and additives as necessary, and then melt kneaded using a known kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a kneader, a roll mill, and the like. It can manufacture by doing.

(Molded article)

The resin composition is processed into a molded article by injection molding.

The conditions during injection molding are not particularly limited and are appropriately selected depending on the shape and size of the target molded article and the type and scale of the injection molding machine used, but the molding temperature is preferably 200 to 260 ° C. If molding temperature is more than the said lower limit, sufficient moldability can be ensured, and if it is below the said upper limit, thermal degradation of a resin composition can be prevented.

Example

In the following examples and comparative examples, "%" means "mass%" and "part" means "mass part".

(Examples 1-10, Comparative Examples 1-10)

Using a polymerization apparatus equipped with all four stages of polymerization reactors in series, the ethylene-propylene copolymer was polymerized in the two stages of polymerization reactors at the front end, and these were fed to the two stages of polymerization reactors, followed by two stages of polymerization. In the reactor, an ethylene-butene copolymer (denoted as "C2C4" in Tables 1 to 3) or an ethylene propylene copolymer (denoted as "C2C3" in Tables 1 to 3) was polymerized. At this time, the propylene resin material shown in Tables 1-3 was obtained by adjusting ethylene supply amount, hydrogen supply amount, polymerization temperature, polymerization pressure, and catalyst addition amount.

0.2 part of crystallization nucleating agents (Millken 3988 by Millenken) was mix | blended with 100 parts of this propylene resin materials, and it melt-kneaded at 230 degreeC using the extruder, and obtained the resin composition.

(Comparative Example 11)

The resin composition (PM-62V by Sun-Allomer Co., Ltd.) which mix | blended the rubber component with the ethylene propylene random copolymer was used.

Melt flow rate (MFR), productivity, transparency, whitening resistance, bending elastic modulus, and impact resistance at low temperatures of each resin composition were evaluated as follows. The evaluation results are shown in Tables 1-3.

[MFR]

MFR is the value measured on condition of temperature 230 degreeC and a load of 21.6N based on JISK7110.

[productivity]

The productivity of the resin composition was evaluated based on the following criteria.

(Double-circle): Continuous production in a polymerization reactor is possible, and production rate is high.

○: Continuous production in the polymerization reactor is possible, and the production rate is medium.

(Triangle | delta): Although continuous production in a polymerization reactor is possible, it is necessary to lower a production speed.

X: Continuous production in a polymerization reactor is impossible.

[Transparency]

Each resin composition was injection-molded at the molding temperature of 230 degreeC, and the plate-shaped test piece of 1 mm thickness was produced. Using this test piece, haze was measured by the haze measuring apparatus (Murakami Color Technical Research Institute HM-150 type | mold) according to JISK7105. The smaller the value of the haze, the better the transparency

[Impact resistance at low temperature, whitening resistance]

Each resin composition was injection-molded at the molding temperature of 230 degreeC, and the plate-shaped test piece of 2 mm thickness was produced. Using this test piece, in a 0 degreeC environment, surface impact strength was measured with the surface impact strength measuring apparatus (Shimadzu Corporation hydro short).

Moreover, each resin composition was injection-molded at the molding temperature of 230 degreeC, and the bottomed hemispherical container was produced. This container was destroyed by the surface impact strength measuring apparatus (hydro shot by Shimadzu Corporation) in 0 degreeC environment. The cracking condition at this time was visually observed and evaluated according to the following criteria.

(Circle): It does not crack and is crushed, and a fragment does not generate | occur | produce.

X: Cracks and debris are formed.

Moreover, except having made temperature into 0 degreeC, the test piece was shocked in the same manner as the measurement of the said surface impact strength, and the whitening resistance was evaluated based on the following references | standards.

(Circle): No whitening was observed.

X: Whitening was observed.

[Flexural modulus]

It was measured according to JIS K 6758.

The resin compositions of Examples 1 to 10 were all excellent in transparency, whitening resistance and low temperature impact strength.

The resin composition of the comparative example 1 whose intrinsic viscosity is 0.7 dl / g was difficult to manufacture the propylene resin material by superposition | polymerization.

The resin composition of the comparative example 2 whose intrinsic viscosity is 1.7 dl / g was low in whitening resistance.

The resin composition of the comparative example 3 containing the ethylene 1-butene copolymer whose ethylene unit is 4.2% was difficult to continuously manufacture the propylene resin material by superposition | polymerization.

The low temperature impact strength of the resin composition of the comparative example 4 which made content of the ethylene 1-butene copolymer into 9% was low.

The resin composition of Comparative Example 5 having an MFR of 20 g / 10 minutes had a low low temperature impact strength.

The low temperature impact strength of the resin composition of the comparative example 6 which made 88% the ethylene unit of an ethylene 1-butene copolymer was low.

The resin composition of the comparative example 7 which made ethylene unit of an ethylene 1-butene copolymer 72% was difficult to manufacture continuously the propylene resin material by superposition | polymerization.

The resin composition of Comparative Example 8 not containing a crystallization nucleating agent had low transparency and rigidity.

The resin compositions of Comparative Examples 9 and 10 in which the rubber component was an ethylene-propylene copolymer had low whitening resistance.

The resin composition of the comparative example 11 which mix | blended the rubber component with the ethylene propylene random copolymer had low low-temperature impact strength.

The polypropylene resin composition for injection molding of the present invention can be suitably used in various packaging containers such as transparent garment cases, food containers, cosmetic containers, container lids with hinges and the like.

Claims (3)

A polypropylene resin composition for injection molding containing a propylene resin material and a crystallization nucleating agent,
The intrinsic viscosity of xylene solubles in tetrahydronaphthalene at 135 ° C is 0.8 to 1.4 dl / g, and the melt flow rate measured at conditions of temperature 230 ° C and load 21.6 N in accordance with JIS K 7210 is 5 to 15 g /. 10 minutes
The said propylene resin material is what superposed | polymerized the ethylene 1-butene copolymer of 74-86 mass% of ethylene units in presence of the ethylene propylene copolymer of 2.0-4.0 mass% of ethylene units,
The polypropylene resin composition for injection molding whose content of the ethylene 1-butene copolymer when the polypropylene resin composition for injection molding is 100 mass% is 10-20 mass%. The method of claim 1,
The polypropylene resin composition for injection molding whose content of a crystallization nucleating agent is 0.01-0.5 mass part with respect to 100 mass parts of propylene resin materials. The molded article which injection-molded the polypropylene resin composition for injection molding of Claim 1 or 2.